With increasing consumer demand, freshwater and saltwater based aquaculture is poised to become a major industry in the United States in the 21st century. In the state of Mississippi, channel catfish farming represents an approximate $260 million industry with strong growth potential.
At the present time, a system to inventory in-situ is not available.
An accurate inventory of ponds to determine biomass is desirable in order to increase production efficiencies. For example, the major portion of costs associated with raising channel catfish are related to the cost of feed and aeration which are directly related to the total number of fish being raised in each pond. An accurate inventory can optimize food and aeration expenditures. Inventories can provide farmers with information utilized for seasonal restocking. Additionally, this information can help provide collateral information as crop insurance and bank loans are contingent upon accurate population estimates. The present invention employs side-scan sonar. Side-scan sonar is a category of sonar system that is commonly used to efficiently create an image of large areas of the sea floor. Thus, this sonar system is frequently used for mapping the seabed for a wide variety of purposes, including creation of nautical charts and detection and identification of underwater objects and bathymetric features. It may be used to conduct surveys for maritime archaeology; in conjunction with seafloor samples it is able to provide an understanding of the differences in material and texture type of the seabed. Side scan sonar imagery is also a commonly used tool to detect debris items and other obstructions on the seafloor that may be hazardous to shipping or to seafloor installations by the oil and gas industry. In addition, the status of pipelines and cables on the seafloor can be investigated using side scan sonar. Side scan data is frequently acquired with bathymetric soundings and sub-bottom data which provides a glimpse of the shallow structure of the seabed. Side scan sonar is also used for fisheries research, dredging operations and environmental studies. It also has military applications including mine detection.
Side scan uses a sonar device that emits fan-shaped pulses down toward the seafloor across a wide angle perpendicular to the path of the sensor through the water, which is typically towed from a surface vessel or submarine, or mounted on the ship's hull. The intensity of the acoustic reflections from the seafloor of this fan-shaped beam is recorded in a series of cross-track slices, which when stitched together along the direction of motion, become an image of the sea bottom within the swath (coverage width) of the beam. The sound frequencies used in side-scan sonar can range from about 100 kHz to about 2.4 MHz and higher. In many conditions, the higher frequencies yield better resolution but less range.
The use of sonar and side scan sonar in some bodies of water, such as commercial catfish ponds, may pose problems with determining the pond's biomass. For example, the side walls can provide erroneous signals or mask fish signals. Additionally, the water is typically very murky, which also contributes to difficulty in reading sonar images. Further contributing to sonar difficulties are the typical soft, silty gaseous pond bottom.
One example of a system for identifying a target in a liquid medium is US Patent Application Publication Number 2005/0270905, incorporated herein by reference, which discloses a use of a side scan sonar. However, this system does not address or solve problems associated with the shallow water environments where the present invention is effective—a catfish pond, for example. Additionally this application fails to address the portability concerns addressed herein.
Thus, there is a substantial need for the present invention.